The present invention relates generally to devices for feeding a traveling strand or the like to a textile or like machine and more particularly relates to such devices of the type including a rotatable storage drum or spool adapted to receive several strand windings circumferentially thereabout for transient storage and delivery of a traveling strand by winding and unwinding thereof onto and off the drum or spool.
As used herein, the term "strand" is intended to generically define and indicate any continuous length material such as yarn, thread, filament, wire, rope, cable, tape or the like.
A relatively wide variety of drum or spool devices of the above-described type are well known in the textile industry and are commonly referred to as "storage feeding devices." Representative examples of such storage feeding devices are disclosed in U.S. Pat. Nos. 3,606,975; 3,642,219; 3,648,939; 3,747,864; 3,796,384; 3,827,645; 3,908,921; 3,928,987; 3,952,554; 4,106,713; 4,114,823; 4,138,866; 4,271,686; 4,457,144; and 4,481,794, and in the Democratic Republic of Germany Patentschrift No. 214112. In basic construction, conventional storage feeding devices of the type of the above-listed patents essentially include a strand storage drum or spool for winding thereabout and unwinding therefrom the traveling strand to be stored and fed, with some arrangement being provided to cause the strand windings to move progressively axially on the drum from the on-winding location to the off-winding location. A pulley or similar driving member is fixedly interconnected coaxially with the drum or spool for integral driven rotation by the associated textile or like machine for effecting the on and off winding of the strand in synchronism to the operation of the associated machine.
One of the important purposes served by such storage feeding devices is to continuously maintain transiently a small quantity of the traveling strand so that, in the event of a breakage in the strand between the strand supply and the textile machine, the breakage can be detected by suitable strand monitoring arrangements and the machine can accordingly be stopped before the broken trailing end of the strand is drawn into the textile machine and can no longer be spliced or otherwise rejoined to the leading broken end of the strand from the strand supply. In this regard, conventional storage feeding devices are typically provided with a strand monitoring arrangement, commonly referred to in the industry as a "stop motion," to detect breakages in the traveling strand. In many conventional storage feeding devices, such a stop motion is arranged to monitor the strand upstream of the storage drum and often a second stop motion is provided to monitor the traveling strand downstream of the storage drum as well.
While such stop motions serve the intended purpose of detecting strand breakages and actuating stoppage of the textile machine, it is common for such stop motions to also deactuate the textile machine for no apparent reason when no breakage of the traveling strand has occurred, commonly called "false stops." While it is not fully known and understood why such false stops occur and some disagreement in the industry exists in this regard, it is believed that natural tension fluctuations and flutterings in the traveling strand between the strand supply and the storage feeding device sometimes permit sufficient movement of the upstream stop motion arrangement to cause deactuation of the associated textile machine.
A number of conventional storage feeding devices are provided with spring-biased tension disks or similar strand braking devices through which the traveling strand is trained upstream of the storage feeding device and its stop motions. The above-listed U.S. Pat. Nos. 3,908,921; 3,928,987; 3,952,554; and 4,106,713 disclose representative uses of such tension disk-type braking devices in conventional storage feeding devices. It is believed that such braking devices are utilized essentially only for the purpose of tensioning the strand in the area of the upstream stop motion in order to prevent false stops.
While such braking arrangements to at least some extent aid in reducing the occurrence of false stops, these braking arrangements create additional more serious problems. Ordinarily, the natural tension existing in a traveling textile strand provides as much tension as is necessary for most textile operations. Accordingly, it is considered undesirable to impose additional tension on a traveling textile strand beyond the minimun amount necessary. Tension disks such as those disclosed in the aforementioned patents and other similar braking arrangements create additional strand tension through the imposition of friction thereon, which may deleteriously cause fraying and lint accumulation when used on spun strands and similar fibrous textile strands, as well as occasional strand breakages when the strand tension level becomes too great. Lint production and accumulation only worsen existing environmental problems in many textile mills and furthermore cause quality control problems by increasing the occurrence of strand slubs. At best, the lint accumulation on the braking devices must be periodically removed, sometimes requiring stopping of the associated textile machine with an attendant reduction in the machine production and efficiency.
One solution to the aforementioned problems is disclosed in co-pending U.S. patent application Ser. No. 784,626, filed by the inventor and applicant hereof on Oct. 4, 1985, and entitled "Strand Storing And Delivering Device." Such application discloses an improved storage feeding device having a pair of spaced upper and lower strand storage drums coaxially mounted integrally with one another for synchronous rotation to transiently store windings of a traveling textile strand in sequence about the upper storage drum and then about the lower storage drum. A stop motion arm monitors the traveling strand intermediate the storage drums to detect strand breakages upstream of the storage feeding device, the upper storage drum effectively isolating the stop motion arm from upstream tension variations, flutterings and the like in the traveling strand so that the stop motion arm detects only actual breakages of the strand. In this manner, the storage feeding device substantially eliminates the occurrence of false stops of the associated textile machine without the use of any strand braking device or otherwise imposing additional tension on the traveling strand.
This improved storage feeding device has been found to be highly effective for its intended purpose of avoiding false stops. However, whenever an actual upstream strand breakage occurs, the stored windings of the strand about the upper storage drum must fully deplete before the breakage is detected by the intermediate stop motion arm, which produces the inconvenience to the operator of the associated textile machine upon each such strand breakage of necessarily having to rewind the broken strand about the upper storage drum as well as rethreading the strand through the intermediate stop motion arm and through associated yarn guides.
It is accordingly an object of the present invention to provide an improvement of the aforedescribed dual drum storage feeding device effective to minimize strand breakages occuring upstream of the device while still fully realizing the advantageous effect of the device to substantially eliminate false stops of the associated textile machine.